Underground pipe pulling process and pipe pull head

ABSTRACT

A pipe pulling technique where an adaptor is attached to the end of the pipe prior to the pipe being pulled underground, for example through a drilled hole. Attaching the adaptor to the pipe end prior to the pipe being pulled underground is faster and reduces danger to workers compared to the conventional process of attaching the adaptor to the end of the pipe after the pipe has been pulled underground.

FIELD

This description relates to pulling pipe underground beneath an obstaclefrom a first side to a second side of the obstacle.

BACKGROUND

It is known to pull a pipe through a borehole drilled in the earthbeneath an obstacle from a first side to a second side of the obstacle.This process can be used to run the pipe underneath the obstacle, suchas a river, a roadway, or the like, from one side to the other.

In the conventional process, a pull head is attached to the pipe at thefirst side. The pipe is then pulled underground through the boreholefrom the first side to the second side. At the second side, the pullhead is removed from the pipe, a section of pipe is then cut from thepipe end, and a pipe adaptor is then fused to the end of the pipe. Theend of a new section of pipe is then joined to the pipe adaptor tocontinue the pipeline.

The fusing or welding of the pipe adaptor to the end of the pipe at thesecond side typically occurs within a trench or bell hole that is dug atthe second side. The trench accommodates the fusing or weldingequipment, the pipe cutting equipment, the pipe pulling equipment andother equipment, as well as personnel operating the equipment. Thetrench or bell hole is typically deep, for example 6 to 8 feet deep.Therefore, the sides of the trench or bell hole need to be reinforced toprevent collapse of the trench onto personnel working in the trench. Inaddition, the trench can be muddy which increases the danger topersonnel working in the trench. Therefore, the process of fusing orwelding the pipe adaptor to the end of the pipe at the second sidewithin the trench can be a lengthy process and it can be dangerous topersonnel.

SUMMARY

A pipe pulling technique is described where the adaptor is attached tothe end of the pipe at the first side prior to the pipe being pulledunderground, for example through a pre-drilled hole. The attachment ofthe adaptor to the pipe at the first side occurs above ground, e.g. notwithin a trench. As a result, attaching the adaptor to the pipe end atthe first side while the pipe end is above ground, and prior to pullingthe pipe underground, is faster and reduces danger to workers comparedto the conventional process of attaching the adaptor at the second sidewithin a trench.

In one embodiment, the pipe and adaptor are both made of plastic, andthe adaptor is attached to the pipe end by fusing the end of the adaptorto the end of the pipe. However, the pipe and the adaptor can be made ofany materials, including but not limited to metal, that are suitable topermit attaching the adaptor and the pipe together in any manner thatsatisfies the intended application(s) of the pipe.

In one embodiment, the pipe can be part of a pipeline that is intendedto carry liquids and/or gases. In another embodiment, the pipe can bepart of pipeline through which cables, for example electrical and/orfiber optic cables, can be run.

The adaptor can be configured to connect to an end of any pipelinecomponent at the second side that is intended to be part of thepipeline. In one embodiment, the adaptor can be a plastic pipe adaptorthat is configured to connect to an end of a second plastic pipe at thesecond side. However, the pipeline component can be a section of pipe, avalve, a coupler that splits flow through the first pipe into multipleflow paths or that gathers flow from multiple flow paths into a singlepath for flow through the first pipe, and other components used inpipelines.

In one embodiment, a method of pulling a pipe underground from a firstside to a second side includes at the first side, attaching an adaptorto an end of the pipe, the adaptor being configured to connect to apipeline component at the second side. At the first side, attaching apull head to the adaptor. The pipe is then pulled underground from thefirst side to the second side by applying a pulling force to the pullhead from the second side. At the second side, the pull head is removed,and the pipeline component is connected to the adaptor.

As used herein, the term “first side” refers to the side at which theend of the pipe is first pulled underground, while the “second side”refers to the side at which the end of the pipe exits after the pipe ispulled underground from the first side. From the perspective of thedrilling equipment used to drill the hole through which the pipe ispulled, the first side may be considered an “exit side” as it is theside through which the drill exits after drilling the hole, while thesecond side may be considered an “entrance side” as it is the sidethrough which the drill initially enters the earth for drilling thehole. Alternatively, from the perspective of the pipe to be pulledunderground, the first side may also be considered an “entrance side” asit is the side through which the end of the pipe being pulled initiallyenters the hole through which the pipe is being pulled, while the secondside may also be considered an “exit side” as it is the side throughwhich the end of the pipe exits the hole after being pulled underground.

In another embodiment, a method of pulling a pipe underground from afirst side to a second side includes at the first side, fusing orwelding a first end of a pipe adaptor to an end of the pipe, a secondend of the pipe adaptor being configured to connect to a pipelinecomponent at the second side. In addition, at the first side, a pullhead is attached to the pipe adaptor after the pipe adaptor is fused tothe end of the pipe. Thereafter, the pipe is pulled underground from thefirst side to the second side by applying a pulling force to the pullhead from the second side. At the second side, the pull head is removed,and the pipeline component is connected to the end of the pipe adaptorafter removing the pull head.

In still another embodiment, a pull head is provided that is used topull a pipe underground from a first side to a second side. The pullhead includes a pull head collar formed by at least first and secondshell pieces that are detachably connectable to one another, where theat least first and second shell pieces are sized to surround an end ofthe pipe when the at least first and second shell pieces are connectedtogether. Each of the at least first and second shell pieces includes aninterior surface and a channel is formed on the interior surface of eachof the at least first and second shell pieces, wherein when the at leastfirst and second shell pieces are connected together the channels of theat least first and second shell pieces align with one another to form asubstantially continuous circumferential channel that in use receives aflange on the pipe. In addition, a pull head cap is connected to firstends of the at least first and second shell pieces when the at leastfirst and second shell pieces are connected together, wherein in use thepull head cap connects to a pull line that applies a pulling force tothe pull head.

DRAWINGS

FIG. 1 illustrates an example application of the pipe pulling techniquedescribed herein.

FIG. 2 is an exploded perspective view of the adaptor attached to theend of the pipe and the parts of the pull head.

FIG. 3 is a cross-sectional side view of the adaptor attached to the endof the pipe and the pull head mounted in place.

FIG. 4 is a perspective view of the pull head mounted in place.

FIG. 5 illustrates an example of a pipe that is connected to the adaptorat the exit side.

FIG. 6 illustrates another example of a pull head.

FIG. 7 illustrates another example of a pull head.

FIG. 8 illustrates still another example of a pull head.

FIG. 9 illustrates still another example of a pull head.

FIG. 10 is a side view of another embodiment of an adaptor attached tothe end of the pipe.

FIG. 11 is a cross-sectional side view of another embodiment of anadaptor attached to the end of the pipe.

FIG. 12 is an exploded view of another embodiment of a pull head.

FIG. 13 shows the pull head of FIG. 12 assembled.

DETAILED DESCRIPTION

FIG. 1 illustrates an example application of the pipe pulling techniquedescribed herein. In this example, a pipeline needs to be extendedunderneath an obstacle 10, such as, but not limited to, a river. Theobstacle 10 could be a roadway, or any other obstacle under which onemay wish to extend a pipeline. The pipeline can be intended to carryliquids and/or gases, or the pipeline can act as a conduit through whichcables, for example electrical and/or fiber optic cables, can be rununderneath the obstacle 10.

A hole 14 is initially drilled into the ground underneath the obstacle10, with the hole 14 extending from a first side 16 on one side of theobstacle 10 to a second side 18 on the other side of the obstacle 10using any suitable directional drilling technique. In one embodiment,the hole 14 is drilled by directional drill equipment the employs adrill that drills into the earth starting from the second side 18 andthat exits the first side 16. Directional drilling is well known in theart. Thereafter, a pipe 20 that forms part of the pipeline is pulledunderground through the hole 14 from the first side 16 to the secondside 18 as indicated by the arrows in FIG. 1. As discussed in furtherdetail below, prior to pulling the pipe 20, an adaptor 30 (seen in FIGS.2-3 and 5) is attached to an end of the pipe 20 at the first side 16,and a pull head 32 is secured around the adaptor 30 at the first side16. A pull line (not shown), such as a cable or rope or pipe, is affixedto the pull head 32 and applies a pulling force to the pull head 32 andthe pipe 20 via a suitable pulling mechanism (not shown) located at ornear the second side 18.

The adaptor 30 will now be described with reference to FIGS. 2-5. Ingeneral, the adaptor 30 is configured to be attached to the pipe 20 ator near the first side 16 while the end of the pipe 20 is above groundand prior to the pipe 20 being pulled underground. The adaptor 30 isalso configured to connect to a pipeline component at the exit side 18that is intended to form part of the pipeline. For example, the pipelinecomponent can be another section of pipe, a valve, a coupler that splitsflow through the pipe 20 into multiple flow paths or that gathers flowfrom multiple flow paths into a single path for flow through the pipe20, and other pipeline components used in pipelines. FIG. 5 illustratesthe pipe 20 and the adaptor 30 after being pulled to the second side 18and connected to a pipeline component 34 in the form of another sectionof pipe.

The adaptor 30 and the pipe 20 can be attached to one another in anymanner so that the adaptor 30 and the pipe 20 are attached togethersubstantially permanently and a liquid-tight joint is formedtherebetween. For example, the adaptor 30 and the pipe 20 can each bemade of plastic and the adaptor 30 and the pipe 20 can be fused, i.e.“welded”, to one another whereby a molecular bond creating aliquid-tight joint is formed between the adaptor 30 and the pipe 20.Fusing of a plastic adaptor to a plastic pipe is well known in the art.If the adaptor 30 and the pipe 20 are made of metal, the adaptor 30 andthe pipe 20 could be welded together using conventional metal weldingtechniques.

Referring to FIGS. 2 and 3, in one embodiment the adaptor 30 is asubstantially cylindrical, tubular structure, and the pipe 20 is alsosubstantially cylindrical. The adaptor 30 has a first end 40, a secondend 42, an exterior surface 44 (best seen in FIG. 5), and an interiorsurface 46. The first end 40 is attached, for example fused, to an end48 of the pipe 20 as shown in FIGS. 3 and 5 to form a liquid-tight joint49 therebetween. In the illustrated example, a thickness t_(a) of theadaptor 30 measured between the exterior surface 44 and the interiorsurface 46 at the first end 40 is substantially equal to the thicknesst_(p) of the pipe 20 at the end 48 so that the interior surface 46substantially forms a continuation of the interior surface of the pipe20. However, in some embodiments, the thickness t_(a) can be differentthan the thickness t_(p).

Between the first end 40 and the second end 42, the exterior surface 44of the adaptor 30 is provided with at least one flange 50 that extendsradially outwardly from the exterior surface 44. The flange 50 isconfigured to engage with the pull head 32 to transfer a pulling forceacting on the pull head 32 to the adaptor 30 and to the pipe 20. Morethan one flange 50 can be used as described further below with respectto FIG. 10. The flange 50 can have any configuration that is suitablefor achieving this function. In one embodiment, the flange 50 iscircumferentially continuous around the entire circumference of theadaptor 30 although other configurations are possible. The flange 50 canbe located anywhere along the length of the adaptor 30 but in theillustrated example, the flange 50 is located closer to the second end42 than it is to the first end 40.

Referring to FIG. 3, a step 51 is formed to the rear of the flange 50,for example integrally extending from the flange 50 and located betweenthe flange 50 and the first end 40. The step 51 helps to reduce loadingapplied to the flange 50 by the pull head 32 so that the flange 50 doesnot take all of the load.

Still referring to FIG. 3, the interior surface 46 defines a portionextending from the first end 40 toward the second end 42 that has asubstantially constant diameter D₁. The constant diameter portionextends up to approximately a location of a front edge 52 of the flange50, where the interior surface 46 increases in diameter to form aportion having a substantially constant diameter D₂ that is larger thanthe diameter D₁. The transition between the two diameters D₁ and D₂forms a shoulder 54. Due to the increase in diameter, the thickness ofthe adaptor 30 at the second end 42 is less than the thickness t_(a) atthe first end 40. In some embodiment, an end of a mechanism 53 forconnecting the pipeline component 34 (see FIG. 5) can abut against theshoulder 54 when the pipeline component 34 is connected to the adaptor30. In other embodiments, the mechanism 53 does not abut against theshoulder 54 as shown in FIG. 5, in which case the shoulder 54 can beeliminated and the interior surface 46 can have a substantially constantdiameter D₁ from end to end.

FIG. 10 illustrates another embodiment of the adaptor 30 that isattached to the end of the pipe 20. In this embodiment, the adaptor 30includes two or more flanges 50 a, 50 b that are spaced apart from oneanother. Each flange 50 a, 50 b can be received within a correspondingchannel, similar to the channel 70 discussed further below, formed bythe pull head 32. In the illustrated example, the flanges 50 a, 50 b canhave the same or similar thickness t_(f) and the same of similar heighth_(f) from the exterior surface 44 of the adaptor 30. A larger number offlanges can be utilized and the flanges can be spaced apart from oneanother or the flanges can abut one another. In addition, the flanges 50a, 50 b can have different thicknesses t_(f) and heights h_(f). Asdiscussed further below, the pull head 32 would be modified accordinglyto engage with the flanges 50 a, 50 b. Any number and sizes of theflanges 50 a, 50 b can be used on the adaptor 30 to give added strengthto pull against while pulling the pipe underground.

FIGS. 3 and 10 illustrate the flange(s) 50, 50 a, 50 b as beingrectangular in side view. However, the flanges 50, 50 a, 50 b can haveother shapes including, but not limited to, round, triangular, etc. whenviewed in side view. In addition, although the flanges 50 a, 50 b areillustrated as being of the same size, the flanges 50 a, 50 b can havedifferent sizes.

In addition, referring to FIG. 11, the use of one or more flanges on theadaptor is not required. Instead, FIG. 11 illustrates an adaptor 30′that includes one or more channels 180 formed in the outer surfacethereof. In one embodiment, the channel(s) 180 is circumferentiallycontinuous about the periphery of the adaptor 30′. However, thechannel(s) 180 need not be circumferentially continuous but can beinterrupted by one or more non-recessed portions. In some embodiments,if required to accommodate pulling forces and forces during use, thethickness of the end of the adaptor 30′ may be increased to betteraccommodate the channel(s) 180. If a channel(s) 180 is used, the pullheads described below will be modified to include corresponding one ormore radially inwardly extending flanges that extend into the channel(s)180 to secure the pull head 32 to the adaptor 30′ and transfer thepulling forces to the adaptor 30′.

Referring now to FIGS. 2-4, an example of the pull head 32 will now bedescribed. The pull head 32 is configured to detachably connect to theadaptor 30 to apply pulling forces to the adaptor 30 and the pipe 20 topull the adaptor 30 and the pipe 20 underground to the exit side 18. Thepull head 32 can have any configuration that is suitable for achievingthis function.

In the embodiment illustrated in FIGS. 2-4, the pull head 32 includes aplurality of pieces that are connectable together. The pull head 32 canhave any number of pieces that are connectable together in order toperform the intended functions of the pull head 32. In one embodiment,the pull head 32 includes a pull head collar 58 that is removablydisposable around the adaptor 30, and a pull head cap 86 that connectsto the pull head collar 58. However, other configurations are possible.

In the example illustrated in FIGS. 2-4, the pull head collar 58includes a plurality of, for example first and second, shell pieces 60a, 60 b that are detachably connectable to one another so as to surroundthe adaptor 30 when the shell pieces 60 a, 60 b are connected together.When there are two of the shell pieces 60 a, 60 b, each of the shellpieces 60 a, 60 b can be configured as a half shell surrounding abouthalf of the adaptor 30. However, in the case of two shell pieces, theshell pieces 60 a, 60 b can be configured to cover more or less thanhalf of the adaptor 30. For example, the shell pieces 60 a, 60 b can besized at ratios of 75/25, 60/40, etc.

For sake of convenience in describing the concepts, the description willhereinafter refer to first and second shell pieces 60 a, 60 b although adifferent number of shell pieces can be used, and the shell pieces 60 a,60 b sized at a 50/50 ratio, i.e. the shell pieces 60 a, 60 b are halfshells. However, other configurations are possible. The first and secondshell pieces 60 a, 60 b are substantially identical in construction toone another. Each shell piece 60 a, 60 b forms a half cylinder with anexterior surface 62, an interior surface 64, a first end 66, and asecond end 68. In the illustrated example, when the pull head collar 58is mounted in place, the first ends 66 terminate at approximately thejoint 49 so that the shell pieces 60 a, 60 b only overlap the adaptor 30and do not overlap, or only minimally overlap, the pipe 20. However, theshell pieces 60 a, 60 b can be sized such that the first ends 66 extendpast the joint 49 so that the shell pieces 60 a, 60 b overlap theadaptor 30 as well as a portion of the pipe 20.

Referring to FIGS. 2 and 3, a channel 70 is formed on the interiorsurface 64 of each of the shell pieces 60 a, 60 b so that when the shellpieces 60 a, 60 b are connected together around the adaptor 30, thechannels 70 of the shell pieces 60 a, 60 b align with one another toform a substantially continuous circumferential channel that in usereceives the flange 50 of the adaptor 30. In addition to the channel 70,the shell pieces 60 a, 60 b each include a smaller channel 71 so thatwhen the shell pieces 60 a, 60 b are connected together around theadaptor 30, the channels 71 of the shell pieces 60 a, 60 b align withone another to form a substantially continuous circumferential channelthat in use receives the step 51 of the adaptor 30

Referring to FIGS. 2 and 4, side edges 72, 74 of each shell piece 60 a,60 b form mating surfaces that abut against and mate with one another toform a joint 76. Fastener holes 78 are formed along the lengths of theside edges 72, 74 that allow passage of fasteners 80, such as bolts,that removably secure the shell pieces 60 a, 60 b to one anothersurrounding the adaptor 30.

The interior surface 64 of each shell piece 60 a, 60 b is also formedwith a friction enhancement section 82, best seen in FIGS. 2 and 3, thatis configured to enhance frictional engagement between the pull head 32and the exterior surface 44 of the adaptor 30. The friction enhancementsection 82 can have any configuration that is suitable for achievingthis function. In the illustrated example, the friction enhancementsection 82 can be formed by teeth, knurling, rubber pads, or otherfriction enhancement features that engage with the exterior surface 44of the adaptor 40. The exterior surface 44 opposite the frictionenhancement section 82 can be substantially smooth or the exteriorsurface 44 can be provided with friction enhancement features thatengage with the friction enhancement features of the frictionenhancement section 82. The friction enhancement features can beintegrally formed with the interior surface 64 of each shell piece 60 a,60 b, or the friction enhancement features can be formed by a separatelayer of material that is fixed to the interior surface 64 or simplydisposed between the interior surface 64 and the exterior surface 44. Inaddition, in the illustrated example, the friction enhancement section82 extends from one side edge 72 to the other side edge 74, is spacedinwardly from and does not extend all the way to the first end 66, andextends toward but stops short of the channel 70. However, other sizesand arrangements of the friction enhancement section 82 are possible.

Returning to FIGS. 2 and 3, each of the shell pieces 60 a, 60 b furtherincludes an inwardly projecting flange 84 adjacent to the end 68thereof. When the shell pieces 60 a, 60 b are connected together, theflanges 84 align with one another to form a substantially continuouscircumferential flange the purpose of which is discussed further below.

The pull head cap 86 of the pull head 32 is disposed at the front end ofthe pull head 32 and is connected to the end 68 of the shell pieces 60a, 60 b when the shell pieces 60 a, 60 b are connected together aroundthe adaptor 30. When the shell pieces 60 a, 60 b are disconnected, thepull head cap 86 can be disconnected from the shell pieces 60 a, 60 b.In another embodiment, the pull head cap 86 can be integrally orpermanently attached to one or more of the shell pieces 60 a, 60 b. Inuse, the pull head cap 86 connects to a pull line, such as a cable orrope or pipe, that applies a pulling force to the pull head 32. The pullhead cap 86 can have any configuration that is suitable for achievingthe functions of the pull head cap 86. In the illustrated example, thepull head cap 86 has a housing member 88, a pull eye 90, and asecurement disk 92.

Referring to FIG. 3, the housing member 88 is a generally hollow,circular disk with a convex front surface 94 and a rearwardly extendingflange 96. A slot 98 is formed in the front surface 94 through which aportion of the pull eye 90 extends forwardly. The pull eye 90 includes ahole 100 for connecting to the pull line. A disk 102 of the pull eye 90is disposed within the housing member 88 and includes a curved surface104 that engages with an interior curved surface of the front surface94.

The securement disk 92 is configured to close the open end of thehousing member 88. In particular, the securement disk 92 includes a disk106 that closely fits within the flange 96 and the securement disk 92and the housing member 88 are then fastened to one another by weldingthe disk 106 to the flange 96. To the rear of the disk 106 is a seconddisk 108 that has a diameter that is less than, greater than, or equalto the diameter of the disk 106. The disks 106, 108 define therebetweena circumferential channel 110 that in use receives the substantiallycontinuous circumferential flanges 84 of the shell pieces 60 a, 60 b tosecure the pull head cap 86 to the shell pieces 60 a, 60 b.

In some embodiments, it is desirable to prevent ingress of moisture,soil and other contaminants into the interior of the pipe 20 whenpulling the pipe 20 underground. The joint 49 between the adaptor 30 andthe pipe 20 is liquid tight and prevents ingress of moisture, soil andother contaminants. In addition, suitable sealing can be providedbetween the pull head 32 and the adaptor 30 to prevent ingress ofmoisture, soil and other contaminants. For example, in the illustratedexample, a circumferential sealing groove 112 can be formed in the outersurface of the disk 108 that is designed to receive a sealing gaskettherein which seals with the interior surface 64 of the shell pieces 60a, 60 b. In addition, the interior surface 64 of each shell piece 60 a,60 b can be formed with a sealing groove 114 which combine to form acircumferential sealing groove that is designed to receive a sealinggasket therein which seals with the exterior surface 44 of the adaptor30. However, other sealing arrangements and configurations can beutilized including a seal between the rear surface of the disk 108 andthe front facing surface of the adaptor 30.

Referring to FIG. 6, another example of a pull head 132 is illustrated.The pull head 132 can be generally similar in construction to the pullhead 32 in that the pull head 132 includes the pull head collar 58formed by the shell pieces 60 a, 60 b, as well as including the pullhead cap 86. However, in this embodiment, the shell pieces 60 a, 60 bare hinged to one another along one of the side edges 72, 74, forexample the side edge 74 in this example. The shell pieces 60 a, 60 bare connected together by one or more hinges 134, for example two of thehinges 134, that permits the shell piece 60 a to open or close relativeto the shell piece 60 b while the shell pieces 60 a, 60 b remainconnected to one another. FIG. 6 shows the shell piece 60 a at an openposition relative to the shell piece 60 b. The shell piece 60 a canswing to a closed position relative to the shell piece 60 b so as to fitaround the adaptor 30 similar to what is shown in FIGS. 3 and 4. Thisembodiment eliminates the need for a second row of fasteners 80 alongthe side edges 74 of the shell pieces 60 a, 60 b. The construction ofthe shell pieces 60 a, 60 b of the pull head collar 58 and the pull headcap 86 are otherwise similar to the construction described in FIGS. 2-4.

FIG. 7 illustrates another example of a pull head 140 that has a pullhead collar 141 that is formed by three shell pieces 142 a, 142 b, 142c. In this example, each shell piece 142 a, 142 b, 142 c coversapproximately 120 degrees, and when the shell pieces 142 a, 142 b, 142 care connected together, they combine to encircle the adaptor 30. Eachshell piece 142 a, 142 b, 142 c is configured generally similarly to theshell pieces 60 a, 60 b, including each shell piece 142 a, 142 b, 142 chaving the channel 70 and the smaller channel 71 the purpose of which isthe same as for the shell pieces 60 a, 60 b. In addition, the pull head140 can include a pull head cap 144 that can be identical inconstruction to the pull head cap 86.

FIG. 8 illustrates another example of a pull head 150 that includes apull head collar 151 that is formed by at least two shell pieces 152 a,152 b, and a pull head cap 154. For sake of convenience, the pipe 20 isnot illustrated in FIG. 8. In this example, the shell pieces 152 a, 152b have a length that is shorter than the length of the shell pieces 60a, 60 b so that an end 156 of each shell piece 152 a, 152 b stops wellshort or forward of the first ends 40 of the adaptor 30. In addition, inthis example, the shell pieces 152 a, 154 include the channel 70 toreceive the flange 50 but do not include the smaller channel 71 for thestep 51 on the adaptor 30. The second end 42 of the adaptor 30 is alsospaced from the disk 108 of the pull head cap 154.

With continued reference to FIG. 8, the pull head cap 154 is generallysimilar in construction to the pull head cap 86. However, the disk 106does not fit within the flange 96. Instead, the end of the flange 96abuts against the face of the disk 106 and the end of the flange 96 isthen welded to the face of the disk 106.

FIG. 9 illustrates another example of a pull head 160 that includes apull head collar 162 and a pull head cap 164. For sake of convenience,the pipe 20 is not illustrated in FIG. 9. The pull head collar 162 canbe formed by two or more shell pieces that are constructed as discussedabove for FIGS. 2-4 and 6-8. In this embodiment, the pull head cap 164is a single piece construction. In addition, instead of having a pulleye 90, the pull head cap 164 includes a central boss 166 that extendsfrom a disk 168. The central boss 166 includes a threaded aperture 170.In use, a threaded connector (not shown) of a pull line will thread intothe aperture 170 to secure the pull line to the pull head 160 whilepulling the pipe underground.

FIGS. 12 and 13 illustrate an embodiment of a pull head 200 that isformed by multiple shell pieces 202 a, 202 b that are connectabletogether around the adaptor using the fasteners 80 (not shown in FIGS.12 and 13). The interior construction of the shell pieces 202 a, 202 bcan be substantially similar to the interior construction of the shellpieces of the pull heads 32, 132, 142, etc. described above. In thisembodiment, the pull head 200 includes a pull head cap 204 that isformed by pull head cap pieces 206 a, 206 b that are integrally formedwith the respective shell pieces 202 a, 202 b so that the shell piece202 a and the pull head cap piece 206 a together form a single, unitaryconstruction, and the shell piece 202 b and the pull head cap piece 206b together form a single, unitary construction. Each pull head cap piece206 a, 206 b includes an opening 208 formed therethrough, where theopenings 208 align with one another when the shell pieces 202 a, 202 bare secured around the adaptor to form a pull eye. Optionally, one ormore fastener openings 210 can be provided on the pull head cap pieces206 a, 206 b that receive fasteners, such as bolts or screws, helpfasten the pull head cap pieces 206 a, 206 b to one another when theshell pieces 202 a, 202 b are secured around the adaptor.

An example operation and use will now be described with reference to theembodiment illustrated in FIGS. 2-4. The embodiments in FIGS. 6-9operate in a similar manner. This example will assume that the pipe 20and the adaptor 30 are plastic and that the pipe 20 and adaptor 30 arefused to one another. However, a similar operation can be performed whenthe adaptor 30 is welded to the end of the pipe. Referring to FIG. 1,the pipe 20 needs to be pulled underground from the first side 16 to thesecond side 18 underneath the obstacle 10. At the first side 16, the end40 of the adaptor 30 is fused to the end 48 of the pipe 20, for examplewhile the end 48 of the pipe 20 is disposed above ground. Therefore, theworkers and equipment that are performing the fusing are working aboveground instead of within a deep trench as with the prior art.Thereafter, the pull head 32 is secured around the adaptor 30 as shownin FIGS. 3 and 4. The pulling force is then applied to the pull head 32from the second side 18. The pulling force pulls the pipe 20 into andthrough the hole 14 until the pull head 32 emerges from the second side18. The pull head 32 is then removed from around the adaptor 30 whichremains in place fused with the pipe 20. Thereafter, the pipelinecomponent 34 is installed to continue the pipeline as shown in FIG. 5.In this example, installing the pipeline component 34 occurs withouthaving to cut-off any part of the pipe 20 or the adaptor 30 at thesecond side 18, or fusing an adaptor to the pipe 20 at the second side18 within a deep trench. So once the adaptor 30 is fused to the pipe 20at the first side 16 and the pipe is pulled underground to the secondside 18, the pull head 32 can be removed and connection to the pipelinecomponent 34 can occur without having to cut the pipe 20 or the adaptor30 or fuse an adaptor to the pipe at the second side 18.

The examples disclosed in this application are to be considered in allrespects as illustrative and not limitative. The scope of the inventionis indicated by the appended claims rather than by the foregoingdescription; and all changes which come within the meaning and range ofequivalency of the claims are intended to be embraced therein.

1. A pull head that is cooperable with an adaptor attached to a pipe topull the pipe, the adaptor having a flange, the pull head comprising: aplurality of shell pieces that are cooperable with each other tosurround the adaptor in a closed position of the shell pieces, the shellpieces include an interior surface that is configured to permit theshell pieces to engage with the flange on the adaptor when the shellpieces are in the closed position and when a pulling force is applied tothe pull head; and a pull eye that is connectable to a pull line thatapplies a pulling force to the pull head.
 2. The pull head of claim 1,wherein the plurality of shell pieces comprise two shell pieces, the twoshell pieces are hinged to one another so that the two shell pieces canmove between an open position and the closed position.
 3. The pull headof claim 1, wherein the plurality of shell pieces comprise two shellpieces, each of the two shell pieces defines a portion of the pull eye.4. A system, comprising: an adaptor having a first end, a second end, aninterior surface, an exterior surface, and a flange extending radiallyoutwardly from the exterior surface, the flange is located between thefirst end and the second end; the pull head of claim 1 that is removablyattachable to the adaptor.
 5. The system of claim 4, wherein the flangeis circumferentially continuous, and the interior surface of the shellpieces defines a circumferentially continuous shoulder that isengageable with the flange.
 6. The system of claim 4, wherein the flangeis positioned closer to the second end than to the first end.
 7. Thesystem of claim 4, wherein the pull eye is integrally formed with theshell pieces.
 8. The system of claim 4, wherein the adaptor issubstantially cylindrical and tubular.
 9. A pull head that is cooperablewith an adaptor attached to a pipe to pull the pipe, the adaptor havinga flange, the pull head comprising: a first shell piece and a secondshell piece, the first and second shell pieces are hinged to one anotherso that the first and second shell pieces can pivot relative to oneanother between an open position at which the pull head can be installedaround the adaptor and removed from around the adaptor and a closedposition at which the first and second shell pieces surround theadaptor; the first and second shell pieces include an interior surfacethat defines a shoulder when the first and second shell pieces are atthe closed position, the shoulder is positioned on the interior surfaceto be located behind the flange on the adaptor when the first and secondshell pieces are in the closed position; and a pull eye connected to thefirst and second shell pieces, the pull eye is connectable to a pullline that applies a pulling force to the pull head.
 10. A system,comprising: an adaptor having a first end, a second end, an interiorsurface, an exterior surface, and a flange extending radially outwardlyfrom the exterior surface, the flange is located between the first endand the second end; the pull head of claim 9 that is removablyattachable to the adaptor.
 11. The system of claim 10, wherein theflange is circumferentially continuous, and the shoulder iscircumferentially continuous.
 12. The system of claim 10, wherein theflange is positioned closer to the second end than to the first end. 13.The system of claim 10, wherein the pull eye is integrally formed withthe first and second shell pieces.
 14. The system of claim 10, whereinthe adaptor is substantially cylindrical and tubular.
 15. A method ofpulling a pipe from a first location to a second location, comprising:at the first location, attaching an adaptor to an end of the pipe wherethe adaptor includes a first end, a second end, an exterior surface, anda circumferentially continuous flange extending radially outwardly fromthe exterior surface, the flange is located between the first end andthe second end; at the first location, attaching a pull head to theadaptor so that a shoulder of the pull head is positioned behind theflange on the adaptor so as to be engageable with the flange when apulling force is applied to the pull head; pulling the pipe from thefirst location to the second location by applying a pulling force to thepull head from the second location; and at the second location, removingthe pull head and thereafter keeping the adaptor attached to the end ofthe pipe.
 16. The method of claim 15, wherein the pipe is plastic andthe adaptor is plastic, and wherein attaching the adaptor comprisesfusing an end of the adaptor to the end of the pipe.
 17. The method ofclaim 15, further comprising: at the second location, connecting apipeline component to the adaptor without detaching the adaptor from thepipe.